Toward Fully Unsupervised Anharmonic Computations Complementing Experiment for Robust and Reliable Assignment and Interpretation of IR and VCD Spectra from Mid-IR to NIR: The Case of 2,3-Butanediol and trans-1,2-Cyclohexanediol

Anno: 2020

Autori: Paoloni L., Mazzeo G., Longhi G., Abbate S., Fusi M., Bloino J., Barone V.

Affiliazione autori: Univ Brescia, Dipartimento Med Mol & Traslaz, I-25123 Brescia, Italy; CNR, INO, I-25123 Brescia, Italy; Scuola Normale Super Pisa, I-56126 Pisa, Italy.

Abstract: The infrared (IR) and vibrational circular dichroism (VCD) spectra of 2,3-butanediol and trans-1,2-cyclohexanediol from 900 to 7500 cm(-1) (including mid-IR, fundamental CH and OH stretchings, and near-infrared regions) have been investigated by a combined experimental and computational strategy. The computational approach is rooted in density functional theory (DFT) computations of harmonic and leading anharmonic mechanical, electrical, and magnetic contributions, followed by a generalized second-order perturbative (GVPT2) evaluation of frequencies and intensities for all the above regions without introducing any ad hoc scaling factor. After proper characterization of large-amplitude motions, all resonances plaguing frequencies and intensities are taken into proper account. Comparison of experimental and simulated spectra allows unbiased assignment and interpretation of the most interesting features. The reliability of the GVPT2 approach for OH stretching fundamentals and overtones is confirmed by the remarkable agreement with a local mode model purposely tailored for the latter two regions. Together with the specific interest of the studied molecules, our results confirm that an unbiased assignment and interpretation of vibrational spectra for flexible medium-size molecules can be achieved by means of a nearly unsupervised reliable, robust, and user-friendly DFT/GVPT2 model.

Giornale/Rivista: JOURNAL OF PHYSICAL CHEMISTRY A

Volume: 124 (5)      Da Pagina: 1011  A: 1024

Maggiori informazioni: Support from the Italian MIUR (PRIN 2017, project Physico-chemical Heuristic Approaches: Nanoscale Theory Of Molecular Spectroscopy (PHANTOMS), prot. 2017A4XRCA), is acknowledged. We are thankful for the computer resources provided by the high performance computer facilities of the SMART Laboratory (http://smart.sns.it/).
Parole chiavi: Vibrational Circular-dichroism; Absolute-configuration; Hydrogen-bond; Perturbative Approach; Basis-sets; Spectroscopy; Molecules; Raman; Intensities; Ethylene
DOI: 10.1021/acs.jpca.9b11025

Citazioni: 24
dati da “WEB OF SCIENCE” (of Thomson Reuters) aggiornati al: 2025-05-18
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